Olefin-based polymers such as ethylene-based polymers and/or propylene-based polymers are produced via various polymerization processes. Ethylene-based polymers, such as, polyethylene is known for use in the manufacture of a wide a variety of articles. The polyethylene polymerization process can be varied in a number of ways to produce a wide variety of resultant polyethylene resins, having different physical properties that render the various resins suitable for use in different applications. It is generally known that ethylene-based polymers can be produced in solution phase loop reactors, in which ethylene monomer, and optionally one or more alpha olefin comonomers, typically having from 3 to 10 carbon atoms, are circulated in the presence of one or more catalyst systems, under pressure, around a loop reactor, by a circulation pump. The ethylene monomers, and optionally one or more comonomers, are present in a liquid diluent, such as an alkane or isoalkane. Hydrogen may also be added to the reactor. The catalyst systems for producing ethylene-based polymers may typically comprise a chromium-based catalyst system, a Ziegler Natta catalyst system, and/or a molecular (either metallocene or non-metallocene) catalyst system. However, there is still a need for new polymerization processes, exhibiting high reactivity toward hydrogen, and capacity for producing higher molecular weight olefin-based polymers under optimum polymerization conditions. These needs have been met by the following invention.